1. Field of the Invention
The invention relates to a device for forming a Jacquard type shed for a loom, and to a loom fitted with such a device. The invention also relates to a method of forming the shed on such a loom.
2. Brief Description of the Related Art
In the field of forming sheds, WO-A-90/01081 discloses electrical control of electric actuators in a Jacquard type loom. EP-A-1 559 816 discloses using computers controlling electric actuators that enable the cords of a Jacquard harness to be moved in order to control displacement of heddles between a high position and a low position, thus enabling the shed to be formed for each pick. A Jacquard harness may have more than 12,000 individually-controlled cords in order to produce a design having more than 20,000 picks.
The shed is defined as the path followed by the heddles over time, so the shed parameters can be the amplitude of the movement, its shape, its offset in time relative to a reference that may be the crossing or its vertical offset relative to a reference plane, possibly the sheet of the yarns at the crossing. When it is appropriate to modify the shed parameters, the weaver needs to proceed with very numerous adjustments of these parameters which adjustments are lengthy, fiddly, and consequently, a source of errors.